Add bd5snpreaders vignette reference and note getsnp Format 5 support

In the Reading SNP data section of usingformat5files.Rmd, add a note that
getsnp works with Format 5, and link to the bd5snpreaders vignette for details
on the buf/con reader variants.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: jimb3

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: BinaryDosage
 Title: Creates, Merges, and Reads Binary Dosage Files
-Version: 1.0.0.9024
+Version: 1.0.0.9025
 Authors@R:
     c(person(given = "John",
              family = "Morrison",

R/RcppExports.R

@@ -41,12 +41,12 @@ OpenFormat5FileC <- function(filename) {
     .Call(`_BinaryDosage_OpenFormat5FileC`, filename)
 }
 
-CloseFormat5FileC <- function(xptr) {
-    invisible(.Call(`_BinaryDosage_CloseFormat5FileC`, xptr))
+CloseFormat5FileC <- function(xptr_sexp) {
+    invisible(.Call(`_BinaryDosage_CloseFormat5FileC`, xptr_sexp))
 }
 
-ReadFormat5SNPC <- function(xptr, start, nbytes, n_samp, dosage, p0, p1, p2) {
-    .Call(`_BinaryDosage_ReadFormat5SNPC`, xptr, start, nbytes, n_samp, dosage, p0, p1, p2)
+ReadFormat5SNPC <- function(xptr_sexp, start, nbytes, n_samp, dosage, p0, p1, p2) {
+    .Call(`_BinaryDosage_ReadFormat5SNPC`, xptr_sexp, start, nbytes, n_samp, dosage, p0, p1, p2)
 }
 
 ReadBinaryDosageDataC <- function(filename, headersize, numsub, snp, dosage, us, base) {

vignettes/usingformat5files.Rmd

@@ -160,7 +160,13 @@ cat("Indices (bytes):", bd5$indices, "\n")
 # Reading SNP data
 
 The `getbd5snp` function decompresses and returns the dosage and genotype
-probability data for a single SNP.
+probability data for a single SNP. The general-purpose `getsnp` function also
+works with Format 5 files and can be used as an alternative.
+
+For details on all three Format 5 SNP reader functions — including
+`getbd5snp_buf` (pre-allocated output vectors) and `getbd5snp_con` (persistent
+file connection for high-throughput loops) — see the
+[Reading SNPs from Format 5 Files](bd5snpreaders.html) vignette.
 
 The function takes the following parameters.